Track system

ABSTRACT

Track system to be mounted on a vehicle in place of a rotatable OEM tire/wheel assembly, including: A frame. A drive wheel is rotatably mounted on the frame, operatively connectable to the drive shaft of the vehicle, and has a diameter of between 65% and 100% of the OEM tire diameter. Leading and trailing idler wheel assemblies are mounted on the frame. An endless track having an inner surface is disposed around the drive wheel, the leading and trailing idler wheel assemblies. The endless track has an unsupported portion between the drive wheel and one of the leading and trailing idler wheel assemblies. The unsupported portion has a length and a center. The unsupported portion deflects a distance of between 8% and 12% of its length on application of a 25-lb. force at its center.

CROSS-REFERENCE

The present application is a continuation-in-part of U.S. patentapplication Ser. No. 14/920,783, filed Oct. 22, 2015, entitled “HighPerformance Track System for a Vehicle”. Through the '783 application,the present application claims priority to U.S. Provisional PatentApplication No. 62/067,153, filed Oct. 22, 2014, entitled “HighPerformance Track System for a Vehicle”. The entirety of both of thoseapplications is incorporated herein by reference.

FIELD

The present technology relates to track systems to be mounted on avehicle in place of a rotatable tire/wheel assembly.

BACKGROUND

Nowadays, there are an ever-increasing number of people who enjoy ridingall-terrain vehicles and other similar off-road vehicles. There aregenerally two main uses for these vehicles, working and riding. In orderto further adapt these vehicles to the increasing variety of terrainsand surfaces on which they are ridden, companies have started to offertrack systems which can be used to replace the wheels on these vehicles.These track systems are mainly designed for working applications.

Generally, a conventional track system assembly comprises a frame, adrive or sprocket wheel, idler wheels, support rollers and an endlesselastomeric track disposed therearound and cooperating therewith. Byusing an endless track instead of regular tire, a track system generallyprovides increased floatation and better traction since the groundcontacting area, (also referred to as the contact patch) of the endlesstrack is generally significantly larger than the contact patch of aregular tire. Also, a smaller sprocket wheel diameter in the order of60% of the OEM wheel diameter has generally been required to compensatefor the increased rolling resistance of the track system.

In short, the larger ground contacting area of the endless trackeffectively spreads the force of the vehicle over a larger area (i.e.increased floatation) and provides additional ground-engaging surface tothe vehicle (e.g. increased traction), but results in a speed loss andhigher gas consumption.

Though the larger contact patch of the endless track of the track systemis generally a significant advantage when the vehicle is ridden on softsurfaces such as snow, mud or sand, the larger contact patch can becomea hindrance when the vehicle is ridden on harder surfaces such asconcrete, asphalt, snow groomed trail or pavement.

Indeed, the larger contact patch generally implies more friction betweenthe track and the ground, making the vehicle more difficult to steer andmaneuver. Also, the smaller sprocket wheel diameter, which is generallyan advantage over soft terrain, becomes a hindrance when riding onharder surfaces (such as a groomed snow trail) because of the top speedloss. This is why tires are generally used over these hard surfaces andterrains, see FIGS. 1 and 2 showing prior art example.

Particularly on a snow groomed trails, tires are still not the bestoption as they have many disadvantages such as lack of traction,difficulty to get out of ruts, high speed instability, corneringinstability, etc.

Hence, there is a need for an improved track system which attempts tomitigate the aforementioned shortcomings.

SUMMARY

It is an object of the present technology to ameliorate at least some ofthe inconveniences present in the prior art.

The shortcomings of the prior art may in some cases be mitigated byproviding a track system having larger diameter sprocket wheel incombination with a lower track tension. In some circumstances, thelarger diameter sprocket wheel and lower track tension allow the tracksystem to achieve better performance than conventional track systems,especially on harder surfaces.

In one aspect, the present technology provides a track system to bemounted on a vehicle in place of a rotatable tire/wheel assembly, thevehicle having a chassis, the rotatable tire/wheel assembly with an OEMtire diameter and an OEM tire width, and a drive shaft, the track systemcomprising:

-   -   a frame;    -   a drive wheel rotatably mounted on the frame, and operatively        connectable to the drive shaft of the vehicle, the drive wheel        having a diameter of between 65% and 100% of the OEM tire        diameter (in the present context of the present disclosure, a        “drive shaft” is a vehicle shaft that rotates to transmit power        from the vehicle's engine, torque, and rotation to a        ground-engaging element (e.g. wheel) of the vehicle);    -   a leading idler wheel assembly mounted on the frame (in the        context of the present disclosure, a “leading” component is the        one (of such components) that is closest to front of the vehicle        when the track system is correctly installed on a vehicle);    -   a trailing idler wheel assembly mounted on the frame (in the        context of the present disclosure, a “trailing” component is the        one (of such components) that is closest to the rear of the        vehicle when the track system is correctly installed on a        vehicle);    -   an endless track having an inner surface (i.e. the        wheel-engaging surface) disposed around the drive wheel, the        leading idler wheel assembly, and the trailing idler wheel        assembly, the endless track having an unsupported portion        between the drive wheel and one of the leading idler wheel        assembly and the trailing idler wheel assembly, the unsupported        portion having a length and a center, the unsupported portion        deflecting a distance of between 8% and 12% of its length on        application of a 25-lb. force at its center.

Original equipment manufacturers (OEMs) of vehicles such as all-terrainvehicles (ATVs), side-by-side vehicles (SSVs), or utility-terrainvehicles (UTVs), etc., (for example those vehicles branded as Polaris™vehicles, or Honda™ vehicles, etc.) sell their newly-manufacturedvehicles from the factory with tires. In the context of the presentdisclosure, those tires that are placed on brand new vehicles sold bythe manufacturers are referred to as OEM tires, notwithstanding the factthat that such vehicles may, in some case, be able to accept tires ofdifferent sizes, makes, or models, than the OEM tires. As an example,ATV tires are typically described by a sequence of three numbersseparated by dashes and/or x's, for example A×B−C (e.g., 25×10−12). Thefirst number in the sequence (e.g. A or 25) is the tire height (tirediameter). The second number in the sequence (e.g. B or 10) is the tirewidth. The third number in the sequence (e.g., C or 12) is the wheeldiameter. An ATV manufacturer may sell its ATVs equipped with 25×10-12tires/wheels, but that same ATV might be able to accept different sizetires (e.g. 26×11−12).

In some embodiments of the present technology, the drive wheel is asprocket wheel having a plurality of teeth. (It is known in the art tohave drive wheels that are not sprocket wheels.) In some suchembodiments of the present technology, the endless track has a pluralityof spaced-apart apertures dimensioned and longitudinally-positionedalong the endless track to intermesh with the teeth of the sprocketwheel. In some such embodiments of the present technology the endlesstrack has a plurality of metallic clips longitudinally-positioned alongthe inner surface of the endless track between the plurality ofapertures.

In some embodiments of the present technology there is a slide railalong a bottom of the frame, the slide rail being positioned withrespect the endless track such that as the endless track rotates theclips contact the slide rail along a lower run of the track.

In some embodiments of the present technology, the inner surface of theendless track has a first plurality of longitudinally-spaceddrive-wheel-contacting guide lugs positioned to engage an inner side ofthe drive wheel, and the inner surface of the endless track has a secondplurality of longitudinally-spaced drive-wheel-contacting guide lugspositioned to engage an outer side of the drive wheel.

In the context of the present disclosure, an “inner” wheel or roller isthat one that is closer to the vehicle when the track system iscorrectly mounted to the vehicle (and steered straight, if applicable).Similarly, an “inner” side of a wheel or roller is that one that facesthe vehicle when the track system is correctly mounted to the vehicle(and steered straight, if applicable). By contrast, in the context ofthe present disclosure, an “outer” wheel or roller that one that isfurther from the vehicle when the track system is correctly mounted tothe vehicle (and steered straight, if applicable). Similarly, an “outer”side of a wheel or roller is that one that faces away from the vehiclewhen the track system is correctly mounted to the vehicle (and steeredstraight, if applicable).

In some embodiments of the present technology, the leading idler wheelassembly has an inner leading idler wheel and an outer leading idlerwheel; and the trailing idler wheel assembly has an inner trailing idlerwheel and an outer leading idler wheel. The inner surface of the endlesstrack has a first plurality of longitudinally-spacedidler-wheel-contacting guide lugs positioned to engage an outer side ofthe outer leading idler wheel and the outer side of the outer trailingidler wheel. The inner surface of the endless track has a secondplurality of longitudinally-spaced idler-wheel-contacting guide lugspositioned to engage an inner side of the inner leading idler wheel andthe inner side of the inner trailing idler wheel. The inner surface ofthe endless track has a third plurality of longitudinally-spacedidler-wheel-contacting guide lugs positioned to engage an inner side ofthe outer leading idler wheel and the inner side of the outer trailingidler wheel. The inner surface of the endless track has a fourthplurality of longitudinally-spaced idler-wheel-contacting guide lugspositioned to engage an outer side of the inner leading idler wheel andthe outer side of the inner trailing idler wheel.

In some embodiments of the present technology, the first plurality oflongitudinally-spaced idler-wheel-contacting guide lugs and the secondplurality of longitudinally-spaced idler-wheel-contacting guide lugshave a same lug spacing, being a first lug spacing. (In the context ofthe present disclosure the “lug spacing” is the longitudinal distancebetween the lateral centerlines of successive lugs.) The third pluralityof longitudinally-spaced idler-wheel-contacting guide lugs and thefourth plurality of longitudinally-spaced idler-wheel-contacting guidelugs have a same lug spacing, being a second lug spacing. The second lugspacing is greater than the first lug spacing. In some such embodimentsof the present technology, the second lug spacing is twice the first lugspacing.

In some embodiments of the present technology, the first plurality oflongitudinally-spaced drive-wheel-contacting guide lugs and the secondplurality of longitudinally-spaced drive-wheel-contacting guide lugs arepositioned to be longitudinally spaced apart from the apertures in theendless track.

In some embodiments of the present technology the first plurality oflongitudinally-spaced idler-wheel-contacting guide lugs are positionedalong an edge of the endless track. The second plurality oflongitudinally-spaced idler-wheel-contacting guide lugs are positionedalong an opposite edge of the endless track.

In some embodiments of the present technology the track system has atleast one support roller assembly mounted on the frame between theleading idler wheel assembly and the trailing idler wheel assembly. Thefirst plurality of longitudinally-spaced idler-wheel-contacting guidelugs, the second plurality of longitudinally-spacedidler-wheel-contacting guide lugs, the third plurality oflongitudinally-spaced idler-wheel-contacting guide lugs, and the fourthplurality of longitudinally-spaced idler-wheel-contacting guide lugseach engage a side of a support roller of the at least one supportroller assembly.

In some embodiments of the present technology, the endless track has awidth of between 75% and 125% of the OEM tire width. In some suchembodiments of the present technology, the width of the endless track isless than 11½ inches.

In some embodiments of the present technology, the unsupported portionhas a length of 15⅜ inches and the unsupported portion deflects adistance of between 1¼ inches and 1¾ inches on application of the 25-lb.force.

In some embodiments of the present technology the drive wheel has adiameter of between 68% and 97% of the OEM tire diameter.

In some embodiments of the present technology the drive is mountable toa wheel hub of the vehicle in place of the rotatable tire/wheel assemblyto attach the track system to the vehicle.

In some embodiments of the present technology, the frame is mountable tothe vehicle to attach the track system to the vehicle.

In some embodiments of the present technology, a track system has asprocket wheel having a larger diameter (when compared with at leastsome conventional track systems' sprocket wheels) such that a ratio ofthe sprocket wheel diameter relative to the OEM tire diameter is between65 to 100%.

In some embodiments of the present technology, a track system has atrack that uses a lower track tension (as compared with at least someconventional track systems), which may improve the track system'sperformance while reducing rolling resistance between the endless trackand the ground.

In some embodiments of the present technology, a track system has anarrower endless track (as compared with at least some conventionaltrack systems), which may also improve driving conditions by potentiallyreducing the rolling resistance on harder surfaces.

In some embodiments of the present technology, a track system mayprovide the vehicle with higher performance compared with at least someconventional track systems because of the synergistic combination of thelarger diameter sprocket wheel (or driving wheel) and lower tracktension.

In some embodiments of the present technology, an endless track has amultiple guide lugs on its inner surface to assist in maintainingalignment of the track with respect to the idler wheels (and potentiallythe support rollers, where they are present), thus attempting todiminish the occurrence of “detracking” of the endless track from thetrack system. (“Detracking” is a term of art describing the situationwhen the endless track becomes misaligned with respect to thewheels/rollers of a track system and may then come off the track systemcompletely.)

In some embodiments of the present technology, a track system forreplacing an OEM tire-wheel assembly of a vehicle, has a frame, asprocket wheel pivotally mounted to the frame and operationallyconnected to a drive shaft of the vehicle, and a plurality of idlerwheel assemblies pivotally mounted to the frame for guiding an endlesstrack disposed around the plurality of idler wheel assemblies and thesprocket wheel. The sprocket wheel has a diameter between 65% and 100%of the diameter of the replaced OEM tire of the vehicle, and the endlesstrack has a tension that is selected to attempt to reduce the occurrenceof detracking of the endless track.

In another aspect, some embodiments of the present technology aredirected to a vehicle equipped with a pair of track systems as definedherein above.

In another aspect, some embodiments of the present technology aredirected to a vehicle equipped with a plurality of pairs of tracksystems as defined herein above.

In another aspect, some embodiments of the present technology aredirected to a track system for replacing a tire-wheel assembly of avehicle, the track system comprising a frame having a slide rail forguiding a lower run of an endless track and for limiting detracking ofthe endless track, a sprocket wheel having teeth rotatably mounted tothe frame and operationally connected to a drive shaft of the vehicle, aplurality of idler wheel assemblies mounted to the frame for guiding theendless track disposed around the plurality of idler wheel assembliesand the sprocket wheel. The endless track has an inner (wheel-engaging)surface, an outer (ground-engaging) surface, widthwise reinforcing rods,and apertures to intermesh with the teeth of the sprocket wheel. Theinner (wheel-engaging) surface has a plurality of guide lugs and, andthe sprocket wheel has a diameter between 65% and 100% of the diameterof the OEM tire of the vehicle, and the endless track has a tension thatis selected to attempt to reduce the occurrence of detracking of theendless (track tension limiting derailment) of the endless track.

In another aspect, some embodiments of the present technology aredirected to a vehicle equipped with a pair of track systems as definedherein above.

In another aspect, some embodiments of the present technology aredirected to a vehicle equipped with a plurality of pairs of tracksystems as defined herein above.

In the context of the present specification, the words “first”,“second”, “third”, etc. have been used as adjectives only for thepurpose of allowing for distinction between the nouns that they modifyfrom one another, and not for the purpose of describing any particularrelationship between those nouns. Thus, for example, it should beunderstood that, the use of the terms “first plurality” and “thirdplurality” is not intended to imply any particular order, type,chronology, hierarchy or ranking (for example) of/between thepluralities, nor is their use (by itself) intended imply that any“second plurality” must necessarily exist in any given situation.

Embodiments of the present technology each have at least one of theabove-mentioned object and/or aspects, but do not necessarily have allof them. It should be understood that some aspects of the presenttechnology that have resulted from attempting to attain theabove-mentioned object may not satisfy this object and/or may satisfyother objects not specifically recited herein.

Additional and/or alternative features, aspects and advantages ofimplementations of the present technology will become apparent from thefollowing description, the accompanying drawings and the appendedclaims.

BRIEF DESCRIPTION OF THE DRAWINGS

For a better understanding of the present technology, as well as otheraspects and further features thereof, reference is made to the followingdescription which is to be used in conjunction with the accompanyingdrawings.

Due to the nature of the present technology, some of the drawingsincluded with the present specification may be schematic in nature, anddo not represent the precise positions of the various componentsrelative to each other. It is intended that persons skilled in the artto whom the present specification is addressed will use the descriptionand the drawings in concert with their common general knowledge to makeand use the various aspects of the present technology.

Also, due to the relatively small size of some of the components of thepresent technology, some of the components illustrated in the drawingsincluded with the present specification may have been exaggerated, tomake them more clearly visible.

Also, to maintain clarity of the interconnections of the variouscomponents of the vehicle and track systems shown in drawings, someparts of the vehicle and/or track system may have been omitted from thedrawings, and some parts of the vehicle and/or track system may havebeen shown transparent to preserve a view of other parts that mayotherwise be at least partially hidden on the drawings.

In the drawings:

FIG. 1 is a front elevation view of a prior art ATV.

FIG. 2 is a right elevation view of the ATV of FIG. 1.

FIG. 3 is a front elevation view of an ATV having a track systemaccording to an embodiment of the present technology.

FIG. 4 is a right elevation view of the ATV of FIG. 3.

FIG. 5 is a perspective view of a track system being an embodiment ofthe present technology.

FIG. 6 is an exploded view of the track system as shown in FIG. 5

FIG. 7 is an outer elevation view of the track system as shown in FIG.5.

FIG. 8 is an exploded view of the track system as shown in FIG. 7.

FIG. 9 is an inner elevation view of the track system as shown in FIG.5.

FIG. 10 is an exploded view of the track system as shown in FIG. 9.

FIG. 11 is a cross sectional view along the line A-A of FIG. 5.

FIG. 12 is a bottom plan view of internal components of the track systemas shown in FIG. 5.

FIG. 13 is a top plan view of internal components of the track system asshown in FIG. 5.

FIG. 14 is an expanded view of a portion of an endless track andsprocket wheel of the track system being an embodiment of the presenttechnology.

FIG. 15 is an upper perspective view the track system as shown in FIG.14.

FIG. 16 is an inside view of a portion of the endless track of the tracksystem as shown in FIG. 14.

FIG. 17 is a perspective view a cross section along axis B-B of theendless track as shown in FIG. 16.

FIG. 18 is a perspective view the portion of the endless track as shownin FIG. 16.

FIG. 19 is front elevated view of a tension tester tool.

FIG. 20 is side elevation view of the track system as shown in FIG. 5during tension measurement with the tool as shown in FIG. 19.

FIG. 21 is a graphic representation of an example measurement of theefficiency of a first vehicle equipped with various track systems ofconfigurations being embodiments of the present technology compared withthat of the vehicle when equipped with an OEM tire/wheel assembly.

FIG. 22 is a graphic representation of an example measurement of theefficiency of a second vehicle equipped with various track systems ofconfigurations being embodiments of the present technology compared withthat of the vehicle when equipped with an OEM tire/wheel assembly.

DETAILED DESCRIPTION

Referring to FIG. 1, there is shown an ATV with a track system 100 beingan embodiment of the present technology. It is to be expresslyunderstood that the track system 100 is merely one implementation of thepresent technology. Thus, the description thereof that follows isintended to be only a description of an illustrative example of thepresent technology. This description is not intended to define the scopeor set forth the bounds of the present technology. In some cases, whatare believed to be helpful examples of modifications to the track system100 may also be set forth below. This is done merely as an aid tounderstanding, and, again, not to define the scope or set forth thebounds of the present technology. These modifications are not anexhaustive list, and, as a person skilled in the art would understand,other modifications are likely possible. Further, where this has notbeen done (i.e. where no examples of modifications have been set forth),it should not be interpreted that no modifications are possible and/orthat what is described is the sole manner of implementing that elementof the present technology. As a person skilled in the art wouldunderstand, this is likely not the case. In addition, it is to beunderstood that the track system 100 may provide in certain instances asimple implementation of the present technology, and that where such isthe case they have been presented in this manner as an aid tounderstanding. As persons skilled in the art would understand, variousimplementations of the present technology may be of a greatercomplexity.

Referring first to FIGS. 1-4, the track system 100 is configured toreplace one of the tire/wheel assemblies 620 of an off-road wheeledvehicle (in the figures illustrated as conventional ATV 600) to assistin improving the floatation and/or traction thereof on some surfaces.ATV 600 has a chassis 610 (shown schematically), drive shafts 252 (shownschematically), and tire/wheel assemblies 620. Each of the tire/wheelassemblies has a wheel 660 and an OEM tire 650. Each OEM tire 650 has anOEM tire diameter 640 and an OEM tire width 630; being the same for allof the tire/wheel assemblies on ATV 600.

In the present embodiment, the track system 100 is configured to be ableto replace both front and rear wheels 620 on ATV. This may be the casefor some embodiments in respect of other, typically small-wheeledvehicles such as an ATV, a UTV, a SSV or other similar recreationalvehicle. This is not always the case, however. In some embodiments ofthe present technology, a track system may be configured to replace onlya rear wheel or a front wheel, or only a left wheel or a right wheel.

Now referring to FIGS. 5-10, in this embodiment, the track system 100 isgenerally triangular in shape. The track system has a drive wheel 110(which in this embodiment is a sprocket wheel and in is generallyreferred to as such in the reminder of this description) configured tobe mounted to the vehicle, specifically to the wheel hub thereof (notshown) in a conventional manner. The drive wheel 110 has an inner side236 and an outer side 238. The track system 100 also has frame 120, aleading (front) idler wheel assembly 130 and a trailing (rear) idlerwheel assembly 140 respectively mounted to the frame 120 at the forwardend 122 and at the rearward end 124 thereof. Each idler wheel assembly130, 140 has two idler wheels in this embodiment. Leading idler wheelassembly 130 has an outer leading idler wheel 204 (which itself has anouter side 212 and an inner side 214) and an inner leading idler wheel206 (which itself has an outer side 218 and an inner side 216). Trailingidler wheel assembly 140 has an outer trailing wheel 208 (which itselfhas an outer side 220 and an inner side 222) and an inner trailing wheel210 (which itself has an outer side 226 and an inner side 224. The idlerwheels 204, 206, 208, 210 of each idler wheel assembly 130, 140 arecapable of free rotation. (In other embodiments, the number of leadingand/trailing idler wheels may differ.)

The track system 100 also has support roller assemblies 150 (alsosometimes known in the art as road wheel assemblies or support wheelassembles) mounted to the frame 120 intermediate the leading idler wheelassembly 130 and the trailing idler wheel assembly 140. The supportrollers (outer support roller 250 and inner support roller 248) of eachassembly 150 are capable of free rotation. In the present embodiment,there are two support roller assemblies 150. In other embodiments, thenumber of support roller assemblies may be larger or smaller (includingzero). In the present embodiment, each support roller assembly 150 hastwo support rollers (an outer support roller 250 and an inner supportroller 248). In other embodiments, the number of support rollers persupport roller assembly may vary.

In the present embodiment, the width 270 of each of the idler wheels204, 206, 208, 210 and the support rollers 248, 250 at their endlesstrack contacting surfaces is the same. In other embodiments, thisrelationship may be different.

An endless track 160 is disposed about the sprocket wheel 110, the idlerwheel assemblies 130, 140 and the support roller assemblies 150, andconfigured to be drivingly engaged by the sprocket wheel 110 (as isdescribed in more detail below).

Still referring to FIGS. 5-10, in the present embodiment, the sprocketwheel 110 has a plurality of teeth 169 extending radially from thecircumferential surface thereof. Also referring to FIG. 14, the endlesstrack 160 has a series of spaced-apart holes 194 dimensioned andlongitudinally-positioned along the endless track to intermesh with theteeth 169 of the sprocket wheel 110. Via this intermeshing, the sprocketwheel 110 drivingly engages the endless track 160 in this embodiment.This configuration is sometimes known in the art as the endless trackbeing “externally driven”. Having an externally driven track, a tracksystem may be able to better withstand lower track tension withoutexperiencing teeth jumps (also referred to as having a ratchetingeffect) which can lead to detracking.

Referring to FIGS. 14-18, in this embodiment, located longitudinally onthe inner surface 162 of the track 160 between successive holes 194 area series of steel clips 192 which contact the teeth 169 of the sprocketwheel as the endless track 110 is being driven. (Thus applying thedriving force at the neutral fiber point in the endless track in thisembodiment.) The clips 192 allow for the operation of the track systemat lower endless track tension with a reduced risk of detracking. Thesetrack clips 192 reduce the friction between the track and sprocket tooth169 thus reducing the resistance generally encountered from theinteraction of the sprocket wheel 110 and endless track 160. These clipsare believed to improve the functioning of the very low tension tracksystem 100. In other embodiments, the track clips are made from anyother suitable hardened material such as other metals (i.e. iron) orpolymers.

Also referring to FIG. 16, disposed along the inner surface 162 of thetrack 160 are several series of guide lugs 168, which are described ingreater detail below. Also referring to FIG. 15, disposed along theouter surface 164 (ground-engaging surface) of the track 160 are severalseries of traction lugs that are configured to engage the ground surface300 over which a vehicle 600 equipped with the track system 100 isoperated.

In the present embodiment, the frame 120 is pivotally mounted to thesprocket wheel 110 assembly (which is mounted to the vehicle 600 wheelhub). In other embodiments, the frame 120 could be mounted directly tothe vehicle (e.g. to the vehicle chassis).

Still referring to FIGS. 5-10, in the present embodiment, the tracksystem 100 has two main characteristics, a larger sprocket wheel sizeand the ability to operate at a lower track tension. These twocharacteristics are preferred to obtain the desired performance from thepresent embodiment of the track system 100. The term ‘performance’ usedthroughout the present specification refers to a track system performingin a similar manner as a tire/wheel assembly, to the extent possible. Assuch, one of the factor used in assessing the performance of a tracksystem is the top speed a vehicle (equipped with such a system) mayreach. Notably, the efficiency of the track system 100 will also impactthe speed of the vehicle.

Additionally, in the present embodiment, the track system 100 isequipped with a narrower track 160 (when compared with conventionaltrack system tracks).

Thus, in some of the embodiments of the present technology (includingthe present one), the track 160 is less than 11½ inches wide.Specifically, in the present embodiment, the endless track 160 isapproximately 11 inches in width (measured laterally from outer edge 242to inner edge 246).

A narrower track may improve the efficiency of track system 100 as wellas potentially provide improved handling and driving capabilities (withcompared with some conventional track systems having wider tracks). Anendless track having such a width is believed to diminish rollingresistance (as least as compared with some conventional track systems)as a narrower endless track can have reduced friction between the ground300 and the endless track 160. A narrower endless track 160 alsoconsumes less energy than a wider endless track (all other things beingequal) when bending around sprocket wheel 110 and leading and trailingidler wheel assemblies 130 and 140 because of the hysteresis in therubber. A narrower track has less rubber to bend (all other things beingequal). In some embodiments of the present technology the endless track160 has a width of between 75% and 125% of the OEM tire width. Suchnarrow tracks are not required, however, and, in some embodiments, tracksystems of the present technology are equipped with tracks having awidth of 11½ inches or greater.

The sprocket wheel 110 has a diameter 274 (FIG. 9) that is from 65 to100% (and typically 68 to 97%) of the diameter 640 of the OEM tire 650the track system 100 replaces. In the present embodiment, a 25-toothsprocket wheel 110 with a 20.1-inch diameter 274 is used in a tracksystem 100 of the present technology to replace a tire/wheel assembly620 of an ATV 600 having an OEM tire 650 with a 29.5-inch diameter 640.In this embodiment, the diameter 274 of the sprocket wheel 110 is 68% ofthe diameter 640 of the OEM tire 650. In another example, in anotherembodiment, a 29-tooth sprocket wheel with a 23.3-inch diameter could beused in a track system of the present technology to replace a tire/wheelassembly of an ATV having an OEM tire with a 24-inch diameter. In suchembodiment, the diameter of the sprocket wheel is 97% of the diameter ofthe OEM tire.

In this embodiment of the present technology, various features of thetrack system allow the track system to be run with lower track tensions(as compared with conventional track systems). For example, by using anexternal-type sprocket wheel 110 (a sprocket wheel of the type where thesprocket wheel's teeth 169 intermesh with the holes 194 in the endlesstrack 160 (to drive the endless track 160) and the sprocket wheelperipheral surfaces contact the clips 192, guidance (alignment) of theendless track 160 with respect to the sprocket wheel 110 is enhancedlowering the risk of “tooth skipping” and detracking.

In addition, on the endless track inner surface 162 of the lower run 266of the track assembly 100, the slide rail 138 (sometimes known as a“guiding slide” in the art) is in continuous contact with the metalclips 192 to assist in enhancing proper track guidance, even at arelatively lower endless track tension. Friction between the endlesstrack 160 and the frame 120 is also generally reduced by having thesprocket wheel 110 contact the steel of the clips 192 instead of rubber,a polymer or the like.

Now referring to FIG. 17, the endless 160 in this embodiment, the body(also known in the art as a carcass) of the endless track 160 is made ofrubber. In other embodiments, the body may be made of any other suitablematerial or combination of materials (e.g. an elastomer(s)). Further, inthis embodiment, the body 268 of the endless track 160 includes lateralreinforcing elements, rods 182. In other embodiments, such lateralreinforcing elements may not be present. In other embodiments, the body268 of the endless track may have longitudinal reinforcing elements(with or without the presence of lateral reinforcing elements.) Examplesof suitable longitudinal reinforcing elements include cables, cords,wire ropes, and the like. Examples of suitable lateral reinforcingelements include rods (such as rods 182), stiffeners or the like.

Referring now to FIGS. 14-18, extending outward from the inner surface162 of the endless track 160 are several longitudinally-extending groupsof guide lugs 168. A first such group of guide lugs 168 arelongitudinally-spaced idler-wheel-contacting guide lugs 200 positionedto engage an outer side 212 of the outer leading idler wheel 204, theouter side 220 of the outer trailing idler wheel 208, and the outersides of outer support rollers 250. A second such group of guide lugs168 are longitudinally-spaced idler-wheel-contacting guide lugs 202positioned to engage an inner side 216 of the inner leading idler wheel206, the inner side 224 of the inner trailing idler wheel 210, and theinner sides of inner support rollers 248. A third such group of guidelugs 168 are longitudinally-spaced idler-wheel-contacting guide lugs 228positioned to engage an inner side 214 of the outer leading idler wheel204, the inner side 222 of the outer trailing idler wheel 208, and theinner sides of outer support rollers 250. A fourth such group of guidelugs 168 are longitudinally-spaced idler-wheel-contacting guide lugs 230positioned to engage an outer side 218 of the inner leading idler wheel206, the outer side 226 of the inner trailing idler wheel 224, and theouter sides of inner support rollers 248. A fifth such group of guidelugs 168 are longitudinally-spaced drive-wheel-contacting guide lugs 232positioned to engage an outer side 236 of the sprocket wheel 110. Asixth such group of guide lugs are longitudinally-spaceddrive-wheel-contacting guide lugs 234 positioned to engage an inner side238 of the sprocket wheel 110. The longitudinally-spaceddrive-wheel-contacting guide lugs 232, 234 are positioned to belongitudinally spaced apart from the apertures 194 and longitudinallyaligned with the clips 192 (and the lugs 230, 232).

Referring to FIG. 16, the guide lugs 200 of the first group of lugs 168have a lug spacing (“LS1-O”) 254 which is the same as the lug spacing256 (“LS1-I”) of the guide lugs 202 of the second group of lugs 168.Thus, LS1-O=LS1-I. The guide lugs 228 of the third group of lugs 168have a lug spacing 258 (“LS2-O”) which is the same as the lug spacing260 (“LS2-I”) of the guide lugs 230 of the fourth group of lugs 168.Thus, LS2-O=LS2-I. In this embodiment, LS2-O/LS2-I are twice that ofLS1-O/LS1-I. (In other embodiments, this relationship may differ.) Theguide lugs 232 of the fifth group of lugs 168 have a lug spacing 262(“LS3-O”) that is the same as the lug spacing 264 (“LS3-I”) of the guidelugs 234 of the sixth group of lugs 168. Thus, LS3-O=LS3-I. In thisembodiment, LS3-O=LS3-I=LS2-O=LS2-I. Also in this embodiment,LS3-O/LS3-I are twice that of LS1-O/LS1-I. (In other embodiments, theserelationships may differ.)

The use of drive lugs 200, 202 positioned at the lateral sides (outerlateral side 240, inner lateral side 244) of the endless track 160enhances the ability of the wheels 204, 206, 208, 210, 250, 248 tosupport the endless track 160. This helps to maintain the properalignment of the track 160, which is important when the vehicle isoperated at a lower track tension to avoid detracking. Furthermore,positioning the drive lugs 200, 202 at the lateral edges (outer edge242, inner edge 246) of the endless track 160 may assist in enabling theendless track 160 to withstand lateral forces that might otherwise causethe endless track 160 to bend. Bending of the endless track is generallynot desirable as it might cause the guide lugs 168 to become misalignedand interfere with one or more of the wheels/rollers 204, 206, 208, 210,250, 248, leading to a detracking.

Now referring to FIGS. 19-20, with respect to this embodiment of thepresent technology, the tension in the endless track 160 of the tracksystem 100 is measured using the resulting tension of a point force at agiven location in the track.

In this embodiment of the present technology, the typical operatingtension of the endless track 160 of the track system 100 can beexpressed as a 1½ inch deflection of the endless track 160 uponapplication of a 25-lb force at the midpoint of an unsupported distance850 between the leading idler wheel assembly 130 and the sprocket wheel110 of about 15⅜ inches. (All measurements described herein being takenon a vehicle that is in operating condition, stationary, and unloaded(having no riders nor cargo).) In this embodiment, an operating tensionexpressed as deflection of between 1¼ inches and 1¾ inches (again, uponapplication of a 25-lb force at the midpoint of an unsupported distance850 between the leading idler wheel assembly 130 and the sprocket wheel110 of about 15⅜ inches) is acceptable as it would not significantlyaffect the performance of the vehicle. (By contrast, conventional tracksystems usually have a tension expressed as a deflection of between ½inch and ¾ inch under similar circumstances.) In other embodiments, forexample, different unsupported distances could (and likely would) resultin other acceptable deflection tolerances/ranges.

More generally, the typical operating tension of an endless track of thetrack system being an embodiment of the present technology can beexpressed as a deflection of the endless track 160 upon application of a25-lb force at the midpoint of an unsupported distance 850 between theleading idler wheel assembly 130 and the drive wheel (sprocket wheel110) (or between the trailing idler wheel assembly 140 and the drivewheel (sprocket wheel 110)) as 10% of the length of that unsupporteddistance. (See FIG. 20.) In other embodiments, the deflection of theendless track (under the conditions described above) ranges between 9%and 11% of the length of the unsupported portion 850. In otherembodiments, the deflection of the endless track (under the conditionsdescribed above) ranges between 8% and 12% of the length of theunsupported portion 850.

Now referring to FIGS. 19-20, a tension testing tool 800 is graded ininches on its lower portion 810 and pounds on its exterior portion 830.This tension tester tool 800 is commonly used to measure track tensionin conventional track systems. (Although it is not required in thecontext of the present technology and other tension testing tools may beused.) To measure the tension of the endless track 160 using the tool800, it is necessary to use a ruler 825 or some other straight object.The user places the ruler 825 between the sprocket wheel 110 and theleading idler wheel assembly 130. Then the user places the tool tension800 at the midpoint of the unsupported portion 850 between the sprocketwheel 110 and the idler wheel assembly 130 and supports it to achievethe desired force (e.g. 25 lbs). This force creates a local deflection840 of the endless track 160 and the amount of the deflection 840 ismeasured. In this embodiment, a force of 25 lbs on the endless track 160yields a total deflection of 1½ inches. The reference measurement (orzero) is the ruler 825 that had been previously placed as describedabove. (Understandably, the 25-lb measurement is used as an example, aperson skilled in the art would understand that tension could bemeasured using another reference force other than 25 lbs., in which casethe deflection measurement should be proportionally adjusted.)

In this embodiment of the present technology, it is believed (withoutintending to be limiting) that the synergistic combination of a largersprocket wheel 110 (compared with conventional track systems), a lowerendless track tension (compared with conventional track systems) and anarrower endless track (compared with conventional track systems) yielda track system, having an improved performance (compared with aconventional track system) and a driving behavior that better resemblesthat when driving the same vehicle using wheels.

Further, in this embodiment, the combination of the larger sprocket sizeand lower track tension provide a reduced rolling resistance caused bythe interaction between the ground 300 and track system 100. By reducingthe rolling resistance, it is thus possible to improve the overallefficiency of the track system 100 thus allowing the track system 100 toattain higher performances than known systems. In addition, in someembodiments, lower track tensions while using an externally drivenallows the track system to attain very high efficiency, which may reachup to 90% efficiency at high speeds.

The efficiency of a track system (including track system 100) can beobtained by: (1) Operating the vehicle with a tire while steeredstraight on a given flat horizontal terrain at a specific engine speed(e.g. in RPM). (2) Determining the velocity of the vehicle (with thetire) under those conditions. (3) Dividing the track system's drive(sprocket) wheel diameter by the tire's diameter to obtain a ratio. (4)Multiplying the velocity (with the tire) determined in step 2 by theratio determined in step 3 to obtain a theoretical velocity (of thevehicle with the track system). (5) Operating the vehicle with the tracksystem under the same conditions as in step 1. (6) Determining thevelocity of the vehicle (with the track system) under those conditions.(7) Dividing the velocity (with the track system) determined in step 6by the theoretical velocity calculated in step 4 and multiplying theresult by 100 to convert the number to a percentage. The percentagecalculated in step (7) is the efficiency of the track system.

As an example, at a given engine speed, the speed of the vehicle whenequipped with a track system having a 20.1-inch diameter sprocket wheel(in place of a tire having a 25-inch diameter) would theoretically beabout 80% of the speed of the same vehicle when equipped with the tire(20.1/25×100=80.4%). At that given speed and on a given terrain, whenequipped with the tire, were that vehicle's travel velocity to be 100km/h, that same vehicle would theoretically have travel velocity ofabout 80 km/h when equipped with the track system. If that were actuallythe case (i.e. that the vehicle's travel velocity were about 80 km/h),the track system's efficiency would be about 100%. However, under mostactual operating conditions, a vehicle equipped with a track system isnot 100% efficient owing to rolling resistance induced by the tracksystem and by the softness of the terrain over which the vehicletravels.

Referring to FIGS. 21-22, exemplary measurement data is provided. InFIGS. 21-22 the efficiency and vehicle speed for different-sized tracksystem sprocket wheels is plotted against engine speed (with tracktension and terrain being the same for all). As can be seen in thegraphs, the 25-tooth sprocket wheel is more efficient in a given RPMrange than a 26-tooth sprocket wheel, even if the vehicle speeds arealmost the same. Thus, all other things being equal, vehicle fuelconsumption would be lower and engine life increased, the more efficientthe track system is.

In the present disclosure, where specific materials for any track system110 component have not been provided, any suitable conventional material(or combination of materials) may be used. Where specific materials forany such component have been provided, any suitable conventionalmaterial may also be used.

Modifications and improvements to the above-described implementations ofthe present technology may become apparent to those skilled in the art.The foregoing description is intended to be exemplary rather thanlimiting. The scope of the present technology is therefore intended tobe limited solely by the scope of the appended claims.

The invention claimed is:
 1. A track system to be mounted on a vehiclein place of a rotatable tire/wheel assembly, the vehicle having achassis, the rotatable tire/wheel assembly with an OEM tire diameter andan OEM tire width, and a drive shaft, the track system comprising: aframe; a drive wheel rotatably mounted on the frame, and operativelyconnectable to the drive shaft of the vehicle, the drive wheel having adiameter of between 65% and 100% of the OEM tire diameter; a leadingidler wheel assembly mounted on the frame; a trailing idler wheelassembly mounted on the frame; an endless track having an inner surfacedisposed around the drive wheel, the leading idler wheel assembly, andthe trailing idler wheel assembly, the endless track having anunsupported portion between the drive wheel and one of the leading idlerwheel assembly and the trailing idler wheel assembly, the unsupportedportion having a length and a center, the unsupported portion deflectinga distance of between 8% and 12% of its length on application of a25-lb. force at its center.
 2. The track system of claim 1, wherein thedrive wheel is a sprocket wheel having a plurality of teeth.
 3. Thetrack system of claim 2, wherein the endless track has a plurality ofspaced-apart apertures dimensioned and longitudinally-positioned alongthe endless track to intermesh with the teeth of the sprocket wheel. 4.The track system of claim 3, wherein the endless track has a pluralityof metallic clips longitudinally-positioned along the inner surface ofthe endless track between the plurality of apertures.
 5. The tracksystem of claim 4, further comprising a slide rail along a bottom of theframe, the slide rail positioned with respect the endless track suchthat as the endless track rotates the clips contact the slide rail alonga lower run of the track.
 6. The track system of claim 2, wherein theinner surface of the endless track has a first plurality oflongitudinally-spaced drive-wheel-contacting guide lugs positioned toengage an inner side of the drive wheel, and a second plurality oflongitudinally-spaced drive-wheel-contacting guide lugs positioned toengage an outer side of the drive wheel.
 7. The track system of claim 2,wherein the leading idler wheel assembly has an inner leading idlerwheel and an outer leading idler wheel; the trailing idler wheelassembly has an inner trailing idler wheel and an outer leading idlerwheel; the inner surface of the endless track has a first plurality oflongitudinally-spaced idler-wheel-contacting guide lugs positioned toengage an outer side of the outer leading idler wheel and the outer sideof the outer trailing idler wheel; the inner surface of the endlesstrack has a second plurality of longitudinally-spacedidler-wheel-contacting guide lugs positioned to engage an inner side ofthe inner leading idler wheel and the inner side of the inner trailingidler wheel; the inner surface of the endless track has a thirdplurality of longitudinally-spaced idler-wheel-contacting guide lugspositioned to engage an inner side of the outer leading idler wheel andthe inner side of the outer trailing idler wheel; the inner surface ofthe endless track has a fourth plurality of longitudinally-spacedidler-wheel-contacting guide lugs positioned to engage an outer side ofthe inner leading idler wheel and the outer side of the inner trailingidler wheel.
 8. The track system of claim 7, wherein the first pluralityof longitudinally-spaced idler-wheel-contacting guide lugs and thesecond plurality of longitudinally-spaced idler-wheel-contacting guidelugs have a same lug spacing, being a first lug spacing; the thirdplurality of longitudinally-spaced idler-wheel-contacting guide lugs andthe fourth plurality of longitudinally-spaced idler-wheel-contactingguide lugs have a same lug spacing, being a second lug spacing; and thesecond lug spacing is greater than the first lug spacing.
 9. The tracksystem of claim 8, wherein the second lug spacing is twice the first lugspacing.
 10. The track system of claim 8, wherein the inner surface ofthe endless track has a first plurality of longitudinally-spaceddrive-wheel-contacting guide lugs positioned to engage an inner side ofthe drive wheel; a second plurality of longitudinally-spaceddrive-wheel-contacting guide lugs positioned to engage an outer side ofthe drive wheel; the first plurality of longitudinally-spaceddrive-wheel-contacting guide lugs and the second plurality oflongitudinally-spaced drive-wheel-contacting guide lugs have a same lugspacing, being a third lug spacing; and the third lug spacing is equalto the second lug spacing.
 11. The track system of claim 10, wherein thedrive wheel is a sprocket wheel having a plurality of teeth; the endlesstrack has a plurality of spaced-apart apertures dimensioned andlongitudinally-positioned along the endless track to intermesh with theteeth of the sprocket wheel; and the first plurality oflongitudinally-spaced drive-wheel-contacting guide lugs and the secondplurality of longitudinally-spaced drive-wheel-contacting guide lugs arepositioned to be longitudinally spaced apart from the apertures.
 12. Thetrack system of claim 7, wherein the first plurality oflongitudinally-spaced idler-wheel-contacting guide lugs are positionedalong an edge of the endless track; and the second plurality oflongitudinally-spaced idler-wheel-contacting guide lugs are positionedalong an opposite edge of the endless track.
 13. The track system ofclaim 7, further comprising at least one support roller assembly mountedon the frame between the leading idler wheel assembly and the trailingidler wheel assembly; and wherein the first plurality oflongitudinally-spaced idler-wheel-contacting guide lugs, the secondplurality of longitudinally-spaced idler-wheel-contacting guide lugs,the third plurality of longitudinally-spaced idler-wheel-contactingguide lugs, and the fourth plurality of longitudinally-spacedidler-wheel-contacting guide lugs each engage a side of a support rollerof the at least one support roller assembly.
 14. The track system ofclaim 1, further comprising at least one support roller assembly mountedon the frame between the front idler wheel assembly and the rear idlerwheel assembly.
 15. The track system of claim 2, wherein, the endlesstrack has a width of between 75% and 125% of the OEM tire width.
 16. Thetrack system of claim 15, wherein the width of the endless track is lessthan 11½ inches.
 17. The track system of claim 1, wherein theunsupported portion has a length of 15% inches and the unsupportedportion deflects a distance of between 1¼ inches and 1¾ inches onapplication of the 25-lb. force.
 18. The track system of claim 1,wherein the drive wheel has a diameter of between 68% and 97% of the OEMtire diameter.
 19. The track system of claim 1, wherein the drive ismountable to a wheel hub of the vehicle in place of the rotatabletire/wheel assembly to attach the track system to the vehicle.
 20. Thetrack system of claim 1, wherein the frame is mountable to the vehicleto attach the track system to the vehicle.